


Purpose and Deliberation

by Chiomi



Category: Fringe (TV), Teen Wolf (TV)
Genre: Banshee Lydia Martin, Crossover, F/F, Gen, Magical Stiles Stilinski, Season/Series 03B Spoilers
Language: English
Status: Completed
Published: 2014-02-14
Updated: 2014-02-14
Packaged: 2018-01-12 02:17:43
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 3,296
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/1180731
Author URL: https://archiveofourown.org/users/Chiomi/pseuds/Chiomi
Summary: <blockquote class="userstuff">
              <p>Cambridge, MA is supposed to be distant from their life in high school, but some things stay familiar: Skype chats with Scott, unexpected werewolves, and dead bodies popping up all over school.</p>
            </blockquote>





	Purpose and Deliberation

**Author's Note:**

  * For [Wolftraps (AlwaysBoth)](https://archiveofourown.org/users/AlwaysBoth/gifts).



> It makes more sense if you're familiar with both canons - through 3A for Teen Wolf and season 4 of Fringe. Basic concepts, though, are that mountain ash (rowan) blocks supernatural creatures and that there are parallel universes where a lot of the people are the same but subtle differences ripple down.
> 
> Rating is for dead bodies and a little bit of gore, though way less than either canon.
> 
> Spectacularly early birthday present for Wolftraps, whose fault everything is.
> 
> Thanks to Verity for answering my dumb questions about Boston and Pat for the beta. I can be found on [tumblr](uswe.tumblr.com).

Lydia packs six kinds of wolfsbane when she goes to MIT, because any more would mean less room for conventional weapons and magic supplies. Allison hooks her up with the contact information for some Boston hunters, too, ones who follow a Code, so she should be able to resupply if she’s ever called on to use any of it.

It’s unpacking that’s a problem, because her roommate settled in first, and there’s a line of mountain ash at the door. At least she’s fucked off somewhere else, so she’s not there to see Lydia flush with rage and call Stiles.

“What’s up? Separation anxiety already?”

She’s spent the better part of a week in his Jeep. Getting to the point of missing him would likely take _years_ of his absence. “Get here now.”

There’s a beat of silence. “I’ll be right there.”

It takes him nearly fifteen minutes, and Lydia’s getting looks. She’d only brought up one suitcase, because the plan was for Stiles to come back after he’d dropped off his stuff anyway, but she’s still taking up room in the hallway. Her door is hanging open, and she’s just sitting there. He flails into her hallway and takes it all in and tries to have a conversation with his eyebrows.

“Just do the thing, Stiles,” she says impatiently. “Not gone, just permeable to me.”

He jerks his thumbs at the open door. “Is it okay if I go in? Less conspicuous.”

Lydia waves a hand, shooing him into her room.

He goes into her room and closes the door most of the way and visibly centers himself. It’s almost interesting to watch, because he’s an entirely different person when he’s working. The ash on the floor rises and billows towards him, drawn to him like it always is. There’s a lot of it, since normal humans have to rely on volume for an unbroken line that’ll stay that way. The ash swirls around him darkly, then trickles out in a thin clockwise stream.

“Make it look the same,” Lydia says.

Stiles nods, and the line thickens, coalescing extravagantly. There’s the usual haptic echo when he closes the line, and then they both look at the leftover ash. Lydia raises her eyebrows at him, and Stiles shrugs, because it’s not like he didn’t pack his own. “Is there anything in her wastepaper basket?”

“Oh, no,” Stiles says, and the rest of the ash dumps itself in there. Stiles grabs the bag as Lydia finally gets to grab her suitcase and drag it into her room. “That all you needed me for?”

“Since you’re here, you can bring up my boxes.”

Stiles heaves a put-upon sigh, but Lydia knows when he leaves that he’ll bring everything up.

*

Stiles’ roommate arrives a couple hours after Stiles has finished unpacking, which means he gets the mattress with the weird stain. His nostrils flare and panic lights his eyes when he looks at Stiles, which was kind of predictable. Stiles got into Harvard on excellent recommendation letters and supernatural channels: of course he’s rooming with a werewolf. So of course Stiles is surprised as hell and fumbles to stand. “Hey! Hi. Not a hunter. I feel like that is suddenly a really important thing to say for absolutely no reason and completely unprompted.” He awkwardly waves at the people behind his new roommate, and then shoves his hands in his pockets where they can stop being embarrassing.

The woman - probably his mom? - pushes the door closed, and the really excessively big blond dude sets down his boxes, seemingly so he can dedicate himself to looming. “Got an awful lot of wolfsbane for someone who’s not a hunter, kid.”

“Beacon Hills pack emissary-in-training, my friends kept getting shot. Uh. The gun is also strictly self-defense, if you can smell that.”

“Wait,” says his new roommate. “Really that Beacon Hills? I thought you had to be from somewhere else, since you never talked about any of the crazy stuff on Facebook.”

“Oh, dude, you guys heard about that stuff? We spend most of our time keeping it quiet.”

“It’s hard to keep trolls quiet.” The woman sets her boxes down, too, and touches her kid on the back of the neck. “Looks like you’ll be okay, sweetie. Call us if you need anything.”

He turns and hugs her hard, tucking his head down into her neck to do some unsubtle scent-marking. Stiles stays very still and tries to look unthreatening. Big and blond just kind of watches him until he gets his turn with the hugging, then they leave. Stiles sags back into his desk chair.

His roommate looks at him consideringly, and loops his thumbs in the straps of his backpack. “So yeah, I’m Greg.”

*

It takes Beth, Lydia’s hunter roommate, two weeks into the semester to figure out that Lydia’s not human. Even then, Lydia’s pretty sure it’s only because she screams some vampires away.

“What are you?” she breathes as Lydia looks disdainfully around the alley.

“Was following the two pretty people into an alley hunting strategy or are you just dumb?”

Beth picks herself up and dusts herself off. “They were young, they weren’t supposed to be able to glamour me that hard. Seriously, though, what are you and how did you even get past the mountain ash I have down?”

Lydia smiles tightly. “If you want a real barrier, get an emissary to do it. It’s what I did.”

Stiles hasn’t been around at all - the stuff they’ve found that they like is closer to his campus - so Beth has no idea who he is, and even if she did it’s not like he screams ‘magic’. Beth falls into the loose, ready position that Lydia recognizes from Allison. “Emissary means you work with werewolves. What was the plan, kill me?”

“Oh, get over yourself,” Lydia says, rolling her eyes. “The plan was Dean’s list, and you being a hunter has yet to be anything but a minor and temporary inconvenience. Are we done yet? Can I go back inside or are you going to try to get yourself killed again?”

*

Greg turns out to be pretty chill once he’s over thinking Stiles will kill him: he’s a born wolf, grew up in pack, and says with complete sincerity that, “It’s great to have someone who knows, since now you can watch my back.”

It makes something itch under Stiles’ skin, mostly an urge to wrap Greg in a blanket and lock him in the room for his own protection before the world eats him alive. Greg’s the one who makes friends easily, though, and gets them invited to parties. Stiles hands him some party wolfsbane so he can actually enjoy himself, and that’s how Stiles ends up the only sober person at the party, deeply resenting his own paranoia.

*

Stiles’s room is spacious, with a view of the Yard. Lydia hates him and wants to stab him in the face, because her room continues to smell persistently odd despite both Febreeze and magic, and his closet actually has appreciable storage space. She sits on the futon under his roommate’s lofted bed and glares at him, just on principle.

“Have you found a shooting range that we can afford yet?”

Stiles makes a face. “Not really? Mostly in that I am straight-up living on scholarships right now.”

Lydia makes a face back at him, aiming for commiserating or something, even though his comparative poverty is mostly an inconvenience. “Worth touching base Allison’s contacts over?”

“Or we could just not and pretend we’re not going to need the skill? Shit’s been quiet, and we’re both plenty lethal even if we get rusty.”

Lydia raises an eyebrow at him, because she’s the only one of them who hasn’t been indoctrinated in firearms practically since birth. Stiles shoulders’ slump, and he sets aside the textbook he’d been nominally studying and grabs his laptop. “My dad doesn’t have any real close friends out here, but I’ll see if there are any cops here he’s friends enough with to get us an in.”

*

They make it almost a solid month without any weird horrible deaths. Lydia had started to contemplate adding extracurriculars other than the Women’s League tea ceremony group. But then one of the kids in her lab shimmers and slides apart in several directions and there’s arterial spray everywhere.

Lydia feels no urge to scream, which is weird as fuck. She stays put as they call the police and, uselessly, paramedics, then obediently follows her instructor to the adjoining room to wait to be allowed to go.

The police have barely started to cordon off the lab when FBI agents swarm in. FBI remains nervewracking: it had taken them months to get rid of McCall. Lydia wraps her arms around her waist and lets her voice tremble when they question her. It’s not hard, because the scene really is upsetting. A doddering man in a cardigan comes up, introducing himself with a smile to every field agent. He starts babbling math, and it’s - well, okay, he’s obviously brilliant, but it’s only almost right.

Lydia points out the error, and he beams at her, happier than anyone she’s ever seen at being told he’s wrong. A blonde senior agent gets her name, then hands her a business card.

*

The second full moon of the semester is mid-week, which means Greg is sticking around. He apologizes beforehand, because it’s his first full moon away from home but he’s got a quiz early the next morning. Stiles calls Scott to check in as soon as it’s late enough that he’ll be out of class, but that’s just habit: they’re a little unbalanced with their favorite non-werewolves unavailable, but September went fine and they’re all anchored.

“I check the nemeton last night,” Scott starts. “It’s the only tree in the forest whose leaves are turning. I think it’s pining for you.” His smirk is nearly audible.

“Shut up, Scotty, you’re not allowed to make tree puns about murderous saplings.” He flops down onto his bed casually, but he’s keeping an eye on Greg. He’s pretty sure Greg’s anchor is his family, and very sure that Greg’s life has been secure enough that he thinks the various fuckery that went on in Beacon Hills is exciting rather than disturbing - an action movie rather than a war story. Stiles is not anticipating a good full moon.

He talks to Scott a bit longer, but Scott’s got setup to do for the pack run, which leaves Stiles with pretending to do homework as he monitors his roommate for the potential necessity of damage control. Which inevitably degrades to actually doing homework while his roommate gets twitchy and fangy and loud in a circle of mountain ash, a silencing spell on the room.

*

The second person to die that semester is also from her lab. Lydia doesn’t even bother with 911 - there’s a panicky TA for that. She calls the agent whose card she’d kept.

“Dunham.”

“Hi, Agent Dunham,” she says. “It’s Lydia Martin from MIT. You came last week for a body that fell apart dramatically. We’ve just had another one.”

“When?”

“Just now,” Lydia says, impatient. “I still - oh. I still have her blood on my shoes.”

“Stay right where you are,” Dunham orders. Then, slightly muffled, “Peter, let’s go.”

They question her a little more attentively this time, and the man in the cardigan is back and poking around again. Agent Dunham smiles softly, all supportive comfort. “You seem to be handling this very well.”

Dammit, she’s been spending too much time with Stiles. Lydia makes her eyes go wide and guileless. “The town I’m from had a lot of animal attacks.”

The man in the cardigan putters over, smiling. “I’m Dr. Walter Bishop. Your equation for the last murder doesn’t fit this one.”

“Of course it would have to be modified with additional data points,” Lydia says before she can think better of it.

He smiles wider, then his face falls, and he turns partly away. “You must bring her back to the lab, Olivia. Either she’s the killer or she’ll be very helpful. I have to run some tests.”

*

The first time anyone sees Cora again is when she slams Stiles into the wall outside Dr. Bishop’s lab. Stiles has had enough practice being thrown around that he keeps both coffee trays clear and only spills a little on himself. It’s still scalding-hot.

“What the fuck are you doing here?”

“Well, I was going to continue my expensive campaign to bribe my way into Lydia’s classified internship, but the whole getting slammed into the wall thing is super nostalgic and seems like a much better plan.”

Cora’s eyes flash gold, and there are way too many people in this hallway. “Lydia is fucking Fringe division?”

“Stiles?” asks Agent Dunham, who seems to mostly find him amusing. “Should I call campus security?”

“Nah,” Stiles says, “this is how her whole family shows affection.”

Cora goes ghost-pale and steps away from him, standing painfully straight with her hands at her sides. “Agent Dunham. I’m Special Adjunct Hale for - on the other side.”

Stiles looks back and forth between them, the way Agent Dunham looks suddenly professionally uncomfortable and is glancing at them. He’s going to kill Lydia for holding out on him. “You guys deal with werewolves?” he demands accusingly.

Both of them look at him and frown.

“Right,” Agent Dunham says. “Inside.” She takes one of Stiles’ coffee trays and nods her head at the door.

*

Cora goes back to the other side, needed an FBI escort to get back to the bridge because she’d run out of money and had no legal identity with which to get more and go back to New York. Lydia wonders what she’d been up to, but doesn’t ask: Cora had ditched them all, and apparently wasn’t even Derek’s sister.

Gene lows, and Lydia slackens her grip immediately. She should not allow her frustration with Cora freaking Hale to translate to being mean to a cow.

*

Cora gets leave in December and sacks herself out on Greg’s futon without so much as asking permission. The scent-marking she does isn’t even in the same world as subtle, and Greg looks like he’s going to cry.

Since she answers Stiles’ questions and buys him Korean barbecue, he’s actually pretty happy to have her there, even if he can’t tell Scott because then Scott would tell Derek and everyone would be sad.

Greg’s bravely pretending that he doesn’t feel threatened, taking notes hunched over his desk.

Cora stretches, wearing nothing but a tank top and a pair of boxers she stole from Stiles’ dresser even though it’s mid-afternoon, rubbing her bare calf over the back of the futon. “Has Stiles told you about the time there was a nogitsune yet?”

Greg looks up wide-eyed. “No?”

It doesn’t matter how she knows, whether she kept up some kind of correspondence with her not-relatives or with someone else or just heard through the grapevine: Stiles doesn’t want to hear Cora’s version of this story. “No,” he says firmly.

“C’mon, Stiles, more people should know that you refuse to even talk about dating Derek because you think you’re only his type because you killed people.” When Greg’s eyes go impossibly wider, Cora’s grin turns evil. “Oh, he hadn’t mentioned that? I mean, half his body count was when he was possessed and some of them were demons anyway, but your doe-eyed roommate here’s a stone cold killer.”

“You sound like Kate Argent,” Stiles says resentfully. All the Argents are weirdly fond of excessive descriptors, but - yeah. The comparison might be more apropos than he ever wants to talk about. Counting the incubus senior year, Derek’s four for four on relationships that end in horrible death, and still on a serial killer streak.

“And you need to realize that you’re not her,” Cora snaps back.

Stiles stands, and goes for his shoes, but Cora grabs him and drags him down on top of her, getting a hard elbow to her ribs as reward. She wraps her arms and legs around him and shoves her face into his neck. “You losers all deserve to be happy.”

He elbows her again for good measure, then laces his fingers through hers.

Greg’s still watching them, paralyzed like a rabbit that just found itself on the freeway.

Stiles sighs. “So this was after we all ritually sacrificed ourselves to the nemeton . . .”

*

Lydia gets high on LSD and breaks a bunch of glass with her voice as a Christmas present to Walter. She’s pretty sure that the LSD is just because Walter likes to see people have a good time, but it’s a chance to get paid to try a Schedule 1 drug. For science. He beams at her for hours over the readings he gets.

Cora and Stiles stop by to take her out for dinner, and in the morning she’s not sure whether to be more embarrassed of the sloppy hug she gave Stiles, the sloppier kiss she gave Cora, or the way she giggled and demanded they make her several different kinds of bacon jelly sandwiches.

It doesn’t matter, though: she and Stiles need to magically purge Cora’s scent from their stuff before they fly home for the holidays. The process requires concentration, as does making sure both her and Beth’s firearms are adequately concealed in the room. Flying with them isn’t really an option, even though it’s domestic, so their awful little room needs to be able to pass inspection even with a mini-arsenal. Beth straps them to the bottom of the bed, both sets of guns in one place because it’s easier for what comes next, when Lydia has to make the lot of it invisible and intangible.

Thank God for internet ordering, because she’s practically comatose after that, and it’s only four clicks to get a lettuce wrap delivered.

*

There are wereporcupines.

Cora swears up and down that they don’t exist even as she’s cleaning wereporcupine blood from under her claws. Her leave this time coincided with finals week, so she’s crankier than usual because they’ve been ignoring her.

“Vampires don’t exist in your universe, though, so I think you’re disqualified from being our supernatural expert here,” Stiles points out from where he’s perched on Dr. Bishop’s bench with his Psych book. Dr. Bishop’s happy to have Stiles there as long as he brings Red Vines and consents to experiments on magic: Agents Farnsworth and Dunham tolerate him because apparently the whole thing with the exploding wolfsbane was less destructive than the usual experiments are. He’s not officially on payroll - he’s not even officially present - but they feed him sometimes, so it’s pretty much a win across the board.

*

The wereporcupines can fly, but one of Lydia’s advantages is that her terrified shrieking makes this particular one waver and drop from the sky already bleeding from various orifices. Cora tears what look like important bits out of it, and then she’s all over Lydia, checking her for scratches and bruises.

Lydia’s got gross monster blood all over her sleeves before she comes back to herself enough to grab Cora’s face. “I’m fine and this is dry clean only,” she says firmly.

Cora drops her hands to Lydia’s hips and holds on. She lets out a hard, shaky breath, and Lydia slides a hand up to cradle the back of her neck. “I need you to be okay,” Cora says quietly, barely above a whisper.

There’s blood on them both, now, a corpse cooling not ten feet away, and Fringe agents starting to swarm. None of it distracts in the least from the sensation of Cora’s mouth as Lydia kisses her, fully and with purpose.


End file.
